Abstract: In order to improve the security of power system communication network in the emerging network security environment and distribution network accessing environment,a forward isolation device based on deep packet inspection and security enhancement is proposed.Based on the principle and vulnerability analysis of the traditional forward isolation device,the field programmable gate array（FPGA）is adopted as isolation island to improve the transmission speed and reduce the error bit rate,the reverse penetrating threat is solved by the deep packet inspection technology,the security of human machine interface（HMI）management is improved by two factor authentication technology,the security of local management is improved by the encryption and authentication technology based on the state secret algorithm.Compared with the traditional forward isolation device,the performance and the security level of proposed device are both improved.Finally,the feasibility of the theory and the practicability of the technology are verified by project application.